During agricultural work, in many cases, the most suitable setting of an agricultural working machine from economical and ecological aspects is dependent on properties of the location of a field respectively being worked upon. In this regard, reference is made in particular to the topographical position of the respective location, which has a resulting influence on the supply of water, light and nutrients to the crops. For example, sunken areas of a field are normally supplied more abundantly with water than elevated areas. Owing to the more abundant water supply, more (and larger) crops grow in the sunken areas than on the elevated areas, which crops can thus be sown more densely in the sunken areas than on the elevated areas. Analogously, it is also the case that more fertilizer is required in the sunken areas than on the elevated areas. The different crop densities also have the effect that, during harvesting, different settings of the harvesting machine are expedient, because for example in the case of a combine harvester, the threshing gaps and screen openings can be selected to be larger in the case of greater material throughputs owing to greater crop densities than in the case of small material throughputs (and/or the harvesting speed can be selected to be higher in the case of low crop densities than in the case of higher crop densities). Aside from the described topography of the field, the soil type also has an influence on the setting of the agricultural working machine because, for example, fewer and smaller crops grow on light sandy soils than on heavy marshy soils. Further influential variables are the proximity to trees providing shade, or to water holes or springs.
In the prior art, this long-known problem of the location-specific setting of working machines is solved by means of setpoint value maps in which data regarding the working machine parameters to be set are stored in georeferenced form. During working, said data are accessed on the basis of the respective position of the working machine, which is detected by means of a satellite-based position determining system such as GPS (cf. DE 101 33 191 A1 for soil working or DE 44 31 824 C1 for harvesting machines), or the area to be cultivated is reproduced in linear form on a storage medium, and during the working of the field, the associated data are accessed in a travel-dependent manner for location-specific activation of the working machine (EP 0 282 639 A2).
EP 0 992 186 A1 describes a method for the cultivation of perennial crops such as grapevines and fruit trees, in which method a three-dimensional map of the field with the locations of the individual crops and the yield thereof is generated and is used for planning of subsequent measures.
On the other hand, it has been proposed that local sensors for detection of the nutrient supply and the other soil properties of the soil to be cultivated be provided on board an agricultural machine, and used for the automatic determination of the respective discharge quantities of seed and fertilizer (DE 40 16 603 A1).
In the case of soil working, it has also been proposed (GB 2 318 652 A) that the towing forces to be imparted for towing a plough be detected in order to measure the soil density and to utilize the latter for the automatic control of the working width of the plough, the engine speed and the forward speed of the tractor.
The previous approaches for the automation of the location-specific control of agricultural working machines accordingly involve either local sensors for detection of soil properties (DE 40 16 603 A1 or GB 2 318 652 A), for which purpose relatively complex and expensive sensors must be provided in order to obtain adequate accuracy in the discharging of the materials and the desired crop production results, or setpoint value maps and position determining systems (EP 0 282 639 A2, DE 101 33 191 A1, DE 44 31 824 C1, EP 0 992 186 A1). The map-based systems are afflicted with the outlay for the creation of a setpoint value map and high costs for a sufficiently accurate position determining system, as a result of which presently only a relatively small proportion of agricultural machines are fitted with such map-based control.